1. Field of the Invention
The invention relates to a photosensitive resin composition for a color filter in a liquid crystal display device; particularly to a photosensitive resin composition for a color filter having the advantages of no bubble display and little color difference before and after development.
2. Description of the Related Art
Presently, color filters are widely applied in the field of office equipment such as color liquid crystal displays, color facsimile machines, color cameras. With the growing market demand, the fabrication technology of color filters is diversified. Currently, the dyeing method, the printing method, the electroplating method, the dispersion method and other manufacturing methods are developed, among which the dispersion method is the mainstream process.
The process of the dispersion method includes: first, dispersing a coloring pigment in a photosensitive resin; next, coating the photosensitive resin on a glass substrate, and then subjecting the glass substrate to exposure and development, to fabricate a specific pattern. After repeating the operation three times, a red (R), green (G) and blue (B) pixel colored layer pattern, and then a protection film can be optionally applied on the pixel colored layer pattern.
The photosensitive resin useful in the process of the dispersion method may be those disclosed in Japanese Patent Application Publication No. 1994-95211 and Japanese Patent Application Publication No. 1996-183819, for example, copolymers obtained through polymerization with (meth)acrylic acid as monomer, which is an alkali-soluble resin of the photosensitive resins.
However, in the manufacturing process of color filters, multiple heat treatment steps are required, for example, a post-bake step and a step of forming a transparent conductive film (ITO film) after formation of the red (R), green (G) and blue (B) pixel colored layer pattern, and the steps are generally performed at a high temperature of 200° C. or more, but if the conventional photosensitive resin is heated for about 1 hr at 180° C., generation of aggregated pigment particles (the particle diameter of common aggregated pigment particles is in the range of 1 to 10 μm) in the pixel colored layer easily occurs; and moreover, the heat resistance of the pixel colored layer is poor.
In order to solve the problem, a photosensitive resin composition disclosed in Japanese Patent Application Publication No. 2001-075273 includes a polymer obtained through polymerization of an unsaturated monomer containing a carboxyl group and a monomer containing a glycidyl group as an alkali-soluble resin of a photosensitive resin. However, a color filter fabricated with the photosensitive resin composition in the prior art has the defect of bubble display and the problem of large color difference after development.
Therefore, how to overcome the defect of bubble display and the problem of large color difference after development to meet the current requirements in the industry is objective to study in the technical field of the present invention.